Surface-Mounted Metal-Organic Frameworks as the Platform for Surface Science: Photoreactivity, Electroreactivity, and Thermal Reactivity

Bisher haben Forscher Modellsysteme wie Einkristallmetalle oder Metalloxide entwickelt, um reale Pulversysteme besser zu verstehen. Es bestehen jedoch immer noch Fragen hinsichtlich der Oberflächenstruktur und Reaktivität von MOFs (Metall-organische Gerüstverbindungen). Glücklicherweise bieten oberflächenorientierte SURMOFs (surface-oriented SURMOFs) einen alternativen Ansatz für den Aufbau von Modellplattformen zur Untersuchung dieser grundlegenden Aspekte von MOFs. Diese Arbeit konzentriert sich auf die organische Photochemie, Elektrokatalyse und thermische Pyrolyse von MOFs aus einer physikalisch-chemischen Perspektive unter Verwendung von Oberflächenwissenschaftstechniken und SURMOF-Plattformen. Das Ziel dieser Arbeit besteht nicht nur darin, das Wissen über MOFs und SURMOFs zu erweitern, sondern auch die Leistungsfähigkeit von Oberflächenwissenschaftstechniken und -methoden im Bereich chemischer Reaktionen zu demonstrieren. Zu diesem Zweck verwendet die Arbeit eine hochmoderne UHV-IRRAS-Apparatur (Ultra-High-Vacuum Infrared Reflection Absorption Spectroscopy). Ein auf der Oberfläche montiertes MOF (SURMOF) Modellsystem mit Azid-Seitenketten wurde erfolgreich hergestellt und genau überwacht, um chemische Veränderungen während des Betriebs zu erfassen. Die umfassenden Ergebnisse, die durch die Kombination von IRRAS mit in situ XRD, MS und XPS erzielt wurden, zeigen, dass die Photoreaktion von Azid durch die Bildung von hochaktiven Nitren-Gruppen initiiert wird, die anschließend mit benachbarten C=C-Bindungen des Gerüsts reagieren und Pyrrol-Derivate durch intramolekulare Aminierung erzeugen. Ein hochwertiges ZIF-67-SURMOF wurde in einem Flüssigphasen-Schicht-für-Schicht-Verfahren hergestellt und erstmals in der Sauerstoffentwicklungskatalyse (OER) eingesetzt. Die katalytisch aktiven Spezies, CoOOH, in den SURMOF-Derivaten wurden identifiziert, was Einblicke in die Mechanismen der strukturellen Transformation und die Struktur-Leistung-Beziehungen bietet. Durch Zugabe von Ni und B wurde die Überspannung auf 375 mV bei 10 mA/cm2 reduziert. Zusätzlich wurden in situ IRRAS und XPS verwendet, um die strukturellen Übergänge von ZIF-67 zu kohlenstoffhaltigen Materialien mit Stickstoffelementen zu enthüllen. NEXAFS-Daten zeigen eine abschließende graphitische Struktur der kohlenstoffhaltigen Materialien nach Pyrolyse bei 900 K. Hoffentlich kann diese Arbeit das grundlegende Verständnis und die Anwendungsfelder von auf MOF und SURMOF basierenden Materialien erweitern

Mid-infrared surface sensing based ontTwo-dimensional materials

(English) Mid-infrared (mid-IR) spectroscopy in the wavelength region between 2 and 20 µm is a powerful technique to identify vibrational absorption signatures of molecules, finding in this way extensive applications in healthcare, environmental monitoring, and chemical analysis. Enhanced IR light-molecules interactions can be achieved by exploiting nanostructured surfaces supporting polaritons – hybrid excitations of light and dipolar elements of matter. Recently, polaritons of two-dimensional van der Waals (2D-vdW) materials unveiled a vibrant playground for mid-IR spectroscopy as they possess remarkable properties such as light trapping at deep nanoscale. This dissertation aims to investigate 2D-vdW materials for technological sensing applications. Hence, we explore the mid-IR sensing performance of nanostructures of widely studied 2D-vdW crystals: graphene (the pioneering vdW material with tunable plasmon polaritons) and hexagonal boron nitride (hBN, sustaining ultralow-loss phonon polaritons). Relevant functionalization layers, such as polymer adsorber and antibodies, are combined with the 2D-vdW nanostructures to create gas and for bio-molecular sensors, respectively. Here, we present three main experimental works of 2D-vdW-based mid-IR molecular sensing. First, we investigate the CO2 detection using graphene nanoribbons functionalized with ultrathin CO2-chemisorbing polyethylenimine (PEI). The localized surface plasmon resonance (LSPR) of graphene is modulated by varying CO2 gas concentration, whose substantial shifts are influenced by the reversible PEI-induced doping of graphene. Second, we examine the phonon-enhanced CO2 detection of hBN nanoresonators functionalized with thin PEI layer. The phonon-polariton resonance is modulated by varying CO2 levels with high signal-to-noise ratio signals. Third, we present a quantitative bioassay by transducing different vitamin B12 target concentrations into LSPR shifts of bio-functionalized graphene nanostructures (subsequent addition of pyrene linkers and recombinant anti-vB12 antibody fragments). Additionally, we observed the same result-trends for the same bioassay using graphene nanostructures fabricated both by small-scale (i.e., electron beam lithography) and large-scale (i.e., nanoimprint lithography) methods. Our proof-of-concept mid-IR sensing experiments show quantitative results for the detection of gas and biomarker with functionalized 2D-vdW nanostructures. The opportunity of combining the mid-IR spectroscopy with industrially large-scale 2D-vdW nanostructures (e.g., nanoimprinted GNH in this dissertation) would enable cost-effective technologies in future developments. This dissertation contributes to the field of 2D-vdW-based mid-IR spectroscopic sensors towards exploring novel designs and improved sensitivity, which eventually could lower the limit of detection for molecular analytes in various applications.(Español) La espectroscopia infrarroja de onda media (mid-IR en inglés) en el rango óptico entre 2 y 20 µm es una potente técnica para identificar las huellas vibracionales de las moléculas, permitiendo así su uso en múltiples aplicaciones como salud, monitoreo medioambiental y análisis químico. Aumentar las interacciones luz-molécula en el IR es posible explotando superficies nano-estructuradas que soportan polaritones – excitaciones hibridas entre la luz y dipolos en la materia. Recientemente, polaritones en materiales bidimensionales de van der Waals (2D-vdW) han revelado un escenario interesante para la espectroscopia en el mid-IR, ya que poseen propiedades remarcables como la de confinar la luz a escala nanométrica. Esta tesis pretende investigar materiales 2D-vdW para su uso tecnológico en aplicaciones de detección. De esta manera, exploramos el rendimiento de la detección en el mid-IR de nanoestructuras de cristales 2D-vdW ampliamente estudiados: grafeno (el material vdW pionero con plasmones-polaritones sintonizables) y el nitruro de boro hexagonal (hBN, que soporta fonones-polaritones con muy bajas perdidas). Capas adicionales para la funcionalización, como polímeros absorbentes y anticuerpos, son combinadas con las nanoestructuras 2D-vdW para crear sensores de gas y biomoleculares, respectivamente. Aquí presentamos tres principales trabajos experimentales para la detección de moléculas con materiales 2D-vdW en el mid-IR. Primero, investigamos la detección de CO2 usando nanoribons de grafeno funcionalizado con una capa ultrafina de polietilenimina (PEI), dada su quimisorción de CO2. La resonancia de plasmón de superficie localizada (LSPR) del grafeno es modulada variando la concentración del CO2, cuyos desplazamientos dependen de un efecto de dopaje quimico reversible inducido por el PEI. Después, examinamos la detección realzada de CO2 con fonones a partir de nanoresonadores de hBN funcionalizados con una capa fina de PEI. La resonancia fonón-polaritón es modulada variando los niveles de CO2 con una gran relación señal/ruido. Finalmente, presentamos un bioensayo cuantitativo a partir de la transducción de distintas concentraciones de vitamina B12 a desplazamientos de LSPR con nanoestructuras bio-funcionalizadas de grafeno (con la posterior adición de enlazadores de pireno y anticuerpos fragmentos de recombinante anti-vB12) Adicionalmente, observamos la misma tendencia de resultados para el mismo bioensayo usando nanoestructuras de grafeno fabricadas con métodos no escalables (i.e., litografía por haz de electrones) y escalable (i.e., litografía por nanoimpresión). Nuestras pruebas de concepto con experimentos de detección con luz mid-IR muestran resultados cuantitativos para la detección de gas y biomarcadores con nanoestructuras 2D-vdW funcionalizadas. La oportunidad de poder combinar la espectroscopia mid-IR con nanoestructuras de materiales 2D-vdW industrialmente escalables (ej., GNH via nanoimpresión en esta tesis) podrían permitir desarrollar tecnologías rentables en el futuro. Esta tesis pretende contribuir en el campo de los sensores para espectroscopia mid-IR basados en materiales 2D-vdW, explorando novedosos diseños y mejorando su sensibilidad, los cuales podrían eventualmente reducir el límite de detección para analitos moleculares en varias aplicaciones.Fotònic

Mid-infrared surface sensing based ontTwo-dimensional materials

(English) Mid-infrared (mid-IR) spectroscopy in the wavelength region between 2 and 20 µm is a powerful technique to identify vibrational absorption signatures of molecules, finding in this way extensive applications in healthcare, environmental monitoring, and chemical analysis. Enhanced IR light-molecules interactions can be achieved by exploiting nanostructured surfaces supporting polaritons – hybrid excitations of light and dipolar elements of matter. Recently, polaritons of two-dimensional van der Waals (2D-vdW) materials unveiled a vibrant playground for mid-IR spectroscopy as they possess remarkable properties such as light trapping at deep nanoscale. This dissertation aims to investigate 2D-vdW materials for technological sensing applications. Hence, we explore the mid-IR sensing performance of nanostructures of widely studied 2D-vdW crystals: graphene (the pioneering vdW material with tunable plasmon polaritons) and hexagonal boron nitride (hBN, sustaining ultralow-loss phonon polaritons). Relevant functionalization layers, such as polymer adsorber and antibodies, are combined with the 2D-vdW nanostructures to create gas and for bio-molecular sensors, respectively. Here, we present three main experimental works of 2D-vdW-based mid-IR molecular sensing. First, we investigate the CO2 detection using graphene nanoribbons functionalized with ultrathin CO2-chemisorbing polyethylenimine (PEI). The localized surface plasmon resonance (LSPR) of graphene is modulated by varying CO2 gas concentration, whose substantial shifts are influenced by the reversible PEI-induced doping of graphene. Second, we examine the phonon-enhanced CO2 detection of hBN nanoresonators functionalized with thin PEI layer. The phonon-polariton resonance is modulated by varying CO2 levels with high signal-to-noise ratio signals. Third, we present a quantitative bioassay by transducing different vitamin B12 target concentrations into LSPR shifts of bio-functionalized graphene nanostructures (subsequent addition of pyrene linkers and recombinant anti-vB12 antibody fragments). Additionally, we observed the same result-trends for the same bioassay using graphene nanostructures fabricated both by small-scale (i.e., electron beam lithography) and large-scale (i.e., nanoimprint lithography) methods. Our proof-of-concept mid-IR sensing experiments show quantitative results for the detection of gas and biomarker with functionalized 2D-vdW nanostructures. The opportunity of combining the mid-IR spectroscopy with industrially large-scale 2D-vdW nanostructures (e.g., nanoimprinted GNH in this dissertation) would enable cost-effective technologies in future developments. This dissertation contributes to the field of 2D-vdW-based mid-IR spectroscopic sensors towards exploring novel designs and improved sensitivity, which eventually could lower the limit of detection for molecular analytes in various applications.(Español) La espectroscopia infrarroja de onda media (mid-IR en inglés) en el rango óptico entre 2 y 20 µm es una potente técnica para identificar las huellas vibracionales de las moléculas, permitiendo así su uso en múltiples aplicaciones como salud, monitoreo medioambiental y análisis químico. Aumentar las interacciones luz-molécula en el IR es posible explotando superficies nano-estructuradas que soportan polaritones – excitaciones hibridas entre la luz y dipolos en la materia. Recientemente, polaritones en materiales bidimensionales de van der Waals (2D-vdW) han revelado un escenario interesante para la espectroscopia en el mid-IR, ya que poseen propiedades remarcables como la de confinar la luz a escala nanométrica. Esta tesis pretende investigar materiales 2D-vdW para su uso tecnológico en aplicaciones de detección. De esta manera, exploramos el rendimiento de la detección en el mid-IR de nanoestructuras de cristales 2D-vdW ampliamente estudiados: grafeno (el material vdW pionero con plasmones-polaritones sintonizables) y el nitruro de boro hexagonal (hBN, que soporta fonones-polaritones con muy bajas perdidas). Capas adicionales para la funcionalización, como polímeros absorbentes y anticuerpos, son combinadas con las nanoestructuras 2D-vdW para crear sensores de gas y biomoleculares, respectivamente. Aquí presentamos tres principales trabajos experimentales para la detección de moléculas con materiales 2D-vdW en el mid-IR. Primero, investigamos la detección de CO2 usando nanoribons de grafeno funcionalizado con una capa ultrafina de polietilenimina (PEI), dada su quimisorción de CO2. La resonancia de plasmón de superficie localizada (LSPR) del grafeno es modulada variando la concentración del CO2, cuyos desplazamientos dependen de un efecto de dopaje quimico reversible inducido por el PEI. Después, examinamos la detección realzada de CO2 con fonones a partir de nanoresonadores de hBN funcionalizados con una capa fina de PEI. La resonancia fonón-polaritón es modulada variando los niveles de CO2 con una gran relación señal/ruido. Finalmente, presentamos un bioensayo cuantitativo a partir de la transducción de distintas concentraciones de vitamina B12 a desplazamientos de LSPR con nanoestructuras bio-funcionalizadas de grafeno (con la posterior adición de enlazadores de pireno y anticuerpos fragmentos de recombinante anti-vB12) Adicionalmente, observamos la misma tendencia de resultados para el mismo bioensayo usando nanoestructuras de grafeno fabricadas con métodos no escalables (i.e., litografía por haz de electrones) y escalable (i.e., litografía por nanoimpresión). Nuestras pruebas de concepto con experimentos de detección con luz mid-IR muestran resultados cuantitativos para la detección de gas y biomarcadores con nanoestructuras 2D-vdW funcionalizadas. La oportunidad de poder combinar la espectroscopia mid-IR con nanoestructuras de materiales 2D-vdW industrialmente escalables (ej., GNH via nanoimpresión en esta tesis) podrían permitir desarrollar tecnologías rentables en el futuro. Esta tesis pretende contribuir en el campo de los sensores para espectroscopia mid-IR basados en materiales 2D-vdW, explorando novedosos diseños y mejorando su sensibilidad, los cuales podrían eventualmente reducir el límite de detección para analitos moleculares en varias aplicaciones.Postprint (published version

Development of nanophotonic biosensor platform towards on-chip liquid biopsy

Liquid biopsy has the potential to enable diagnosis, prognosis, and monitoring of some diseases at an early stage using body fluids from patients. This minimally invasive, label-free detection method is less likely to harm the cell’s viability through binding to the surface protein. Smart integration of liquid biopsy designs with microfluidics on a single chip will lead to a considerable reduction in the detection time (due to controlled diffusion length), and the volumes of sample, agent and reagent, and the limit of detection. Optical label-free biosensors are a powerful tool to analyze biomolecular interactions and have been widely studied in the field of biomedical and biological science and engineering. Label-free detection enables direct measurement of key characteristic properties of the chemical compound, DNA molecule, peptide, protein, virus, or cell, while eliminating experimental uncertainty induced by the effect of the label on molecular conformation, thus reducing the time and effort required for bioassay. Existing optical label-free biosensors suffer from three limitations, including low detection sensitivity, slow molecules mass transfer, and poor throughput. The goal of this dissertation is to overcome these limitations through the development of a novel and efficient modality towards liquid biopsy-based bioassay with increased detection sensitivity, speed, and throughput. To increase the detection sensitivity, we investigate the optical bound states in the continuum (BIC) of slotted high-contrast grating (sHCG) structures. We demonstrate that the sHCG support BICs and high-Q resonant modes, and the slot position can be utilized to tune and optimize the linewidth of the high-Q resonances. To overcome the mass-transfer limitation and reduce the assay time, we propose a lateral flow-through optical biosensor integrating high-contrast gratings and microfluidics on a silicon-on-insulator platform. The biosensor design allows reducing the diffusion length to a submicron scale and enhancing direct interactions between the analytes and sensing structures. Finally, we develop a high-throughput, label-free exosome vesicles (EVs) detection microarray formed on a photonic crystal (PC) biosensor surface. We design and implement a hyperspectral imaging approach to quantify the antibody and EV absorptions on the PC-based microarray consisting of a panel of seven antibodies specific to multiple membrane receptors of the target EVs. We validate that the EV microarray by adopting it to detect EVs released by macrophages for the analysis of immune responses

Dynamic Nanophotonic Structures Leveraging Chalcogenide Phase-Change Materials

Chip-scale nanophotonic devices have the potential to enable next-generation imaging, computing, communication, and engineered quantum systems with very stringent performance requirements on size, power, integrability, stability, and bandwidth. The emergence of meta-optic devices with deep subwavelength features has enabled the formation of ultra-thin flat optical structures to replace bulky conventional counterparts in free-space applications. Nevertheless, progress in meta-optics has been slowed due to the passive nature of existing devices and the urgent need for a reliable, fast, low-power, and robust reconfiguration mechanism. In this research, I devised a new material and device platform to resolve this challenge. Through detailed theoretical design, nanofabrication, and experimental demonstration, I demonstrated the unique features of my proposed platform as an essential building block of truly scalable adaptive flat optics for the active manipulation of optical wavefronts. One of the key attributes of this research is the integration of CMOS-compatible materials for the fabrication of passive devices with phase-change materials that provide the largest known modulation of the index of refraction upon stimulation with an optical or electrical signal. A unique selection of phase-change materials for operation in the near-infrared and visible wavelengths has been made, followed by developing the optimum deposition and fabrication processes for the realization of nanophotonics devices that integrate these functional materials with semiconductor and plasmonic materials. A major breakthrough in this process was the design and realization of integrated electrical stimulation circuitry with far better performance compared to existing solutions. Using this platform, I experimentally demonstrated the first electrically tunable meta-optic structure for fast optical switching with a high contrast ratio and dynamic wavefront scanning with a large steering angle. This is a major achievement as it essentially allows the engineering of a desired optical wavefront with fast reconfigurability at low power consumption. In an independent work, I demonstrated, for the first time, a nonvolatile meta-optic structure for high-resolution, wide-gamut, and high-contrast microdisplays with added polarization controllability and the possibility of implementation on a flexible substrate. Further features of this metaphotonic display include: 1) full addressability at the microscale pixel via fast electrical pulses; 2) super-resolution pixels with controllable brightness and contrast; and 3) a wide range of colors with high saturation and purity. Lastly, for the first time, I realized a hybrid photonic-plasmonic meta-optic platform with active control over the spatial, spectral, and temporal properties of an optical wavefront. This is a major achievement as it essentially allows the engineering of a desired optical wavefront with fast reconfigurability at low power consumption. These demonstrations are now being pursued in different directions for novel systems for imaging, sensing, computing, and quantum applications, just to name a few.Ph.D

Nanoreactors for local production and release of antibiotic

Implant infections are emerging as a grave medical problem.The number of medical and surgical procedures involving medical implant devices will continue to grow, for example due to aging of the population. Device-associated infections are a consequence of bacterial adhesion and subsequent biofilm formation at the implantation site. Due to the importance of this problem, intense research is being focused on finding new, efficient treatments. Conventional antibiotic therapies remain ineffective and very often lead to removal of the contaminated device. Various alternative strategies have been proposed, however, these suffer from many drawbacks. Tackling infections associated with medical implants remain a challenge. In this thesis, enzymatically active, covalently immobilized nanoreactors based on poly(2-methyloxazoline)-block-poly(dimethylsiloxane)-block-poly(2-methyloxazoline) (PMOXA-b-PDMS-b-PMOXA) amphiphilic block copolymer were designed and prepared. These nanoreactors catalyzed the conversion of prodrug molecules, which exhibit no antibacterial activity, to a drug active as an antibiotic. The enzymatic conversion was shown to occur only inside the nanoreactors. When these are immobilized they represent a novel, nanosized system whereby a drug will not be released to the entire body, but will be synthesized in situ. This strategy offers multiple advantages: long term production of antibacterial compounds due to the protection of the enzyme from proteolytic degradation, control of drug production at a specific rate for a specific period of time, and localized drug delivery. First, cationic ring opening polymerization was employed to synthesize the polymer. The self-assembly of this polymer was studied, as was the enzymatic activity of the resulting nanoreactor. The covalent attachment of the nanoreactors to a surface was realized by two different strategies: (i) attachment via an amino bond, involving Schiff base formation and its further reduction (ii) attachment via photo-cleavage by a phenyl azido linker. Both approaches resulted in successful, stable immobilization. The attached nanoreactors were characterized by surface-sensitive techniques such as scanning electron microscopy and atomic force microscopy. Experiments with bacteria were conducted to demonstrate the antimicrobial potential of surface immobilized enzymatically active nanoreactors. In summary, this thesis develops the concept of polymeric nanoreactors that synthesize drugs in situ to inhibit bacterial growth. Additionally, the immobilization methodologies elaborated within the scope of this work could be further adapted for potential applications in biotechnology and biosensing

Applications of 2D-layered palladium diselenide and its van der Waals heterostructures in electronics and optoelectronics

The rapid development of two-dimensional (2D) transition-metal dichalcogenides has been possible owing to their special structures and remarkable properties. In particular, palladium diselenide (PdSe2) with a novel pentagonal structure and unique physical characteristics have recently attracted extensive research interest. Consequently, tremendous research progress has been achieved regarding the physics, chemistry, and electronics of PdSe2. Accordingly, in this review, we recapitulate and summarize the most recent research on PdSe2, including its structure, properties, synthesis, and applications. First, a mechanical exfoliation method to obtain PdSe2 nanosheets is introduced, and large-area synthesis strategies are explained with respect to chemical vapor deposition and metal selenization. Next, the electronic and optoelectronic properties of PdSe2 and related heterostructures, such as field-effect transistors, photodetectors, sensors, and thermoelectric devices, are discussed. Subsequently, the integration of systems into infrared image sensors on the basis of PdSe2 van der Waals heterostructures is explored. Finally, future opportunities are highlighted to serve as a general guide for physicists, chemists, materials scientists, and engineers. Therefore, this comprehensive review may shed light on the research conducted by the 2D material community.Web of Science131art. no. 14

Toward The Development Of Printable Perovskite Solar Cells

PSCs have become a significant performer in third generation photovoltaics with power conversion efficiency, greater than 22% for active areas less than 1 cm2. However, with efficiency improvement, concerns regarding the operational stability and industrial production firstly resolved to grow into commercially viable PSCs. To address above stated issues most stable, yet efficient Monolithic PSCs (mPSCs) are structured. The mPSCs are having compact TiO2, mesoporous TiO2, mesoporous ZrO2, and mesoporous carbon electrode layers in optimal thicknesses on the FTO substrate. Fabrication protocol for all the layers which is easily scalable for large area mPSCs manufacturing is highly required. Furthermore top carbon electrode materials those are stable and behaves as protective casing to make PSCs stable has also been highly desired. Hence, in this project our aim is to optimize top carbon layer and study photophysical processes inside the mPSCs. This research work is mainly divided into three parts. The first part of the dissertation described carbon film fabrication by screen printing technique and their investigation at different annealing temperature . Influence of annealing temperatures on the electrical, morphological and structural properties of the carbon film has been discussed. It is shown that a low annealing temperature is good for better adherence of the conductive carbon films, however, temperatures higher than 300°C are required to produce efficient mPSCs. A sintering temperature of 400°C showed the highest device efficiency of 13.2%. It is important to correlate all the physical properties/processes taking place in the mPSCs to gain a deeper understanding of mPSCs operation: What is the role of the contacts? What limits the efficiency of existing perovskite solar cells? How many charge carriers are there in the cell under operating condition. Hence, in second part, Electrochemical Impedance spectroscopy (EIS) spectrum has been described, which is performed on the mPSCs having highest efficiency during previous experiments. The EIS spectrum of mPSCs quantitatively explains the role of contacts, layers, charge generation, drift and diffusion of charge carriers and recombination. This would further provide insight into the performance-limiting physical processes of mPSCs. The microstructure or morphology of the perovskite crystals inside mesoporous TiO2 and mesoporous ZrO2 have significant effect on the mPSCs performance and stability. Therefore, to achieve higher mPSCs device performance, one-dimensional microrods (4mm-5mm) of PbI2 and CH3NH3PbI3 (MAPbI3) is fabricated in the 3rd part. These microrods consist of unique structural and morphological properties which are grown at room temperature. The XRD and TEM analyses confirm the existence of strong interactions between different stable groups in the crystals. The morphological studies approve crack free morphology of PbI2 and MAPbI3 micro-rods. The above results are expected to have a big effect on solar cell and photo-detection industry by fostering improvement of thin-film opto-electronic devices

The Art of Constructing Black Phosphorus Nanosheet Based Heterostructures: From 2D to 3D

Assembling different kinds of 2D nanosheets into heterostructures presents a promising way of designing novel artificial materials with new and improved functionalities by combining the unique properties of each component. In the past few years, black phosphorus nanosheets (BPNSs) have been recognized as a highly feasible 2D material with outstanding electronic properties, a tunable bandgap, and strong in-plane anisotropy, highlighting their suitability as a material for constructing heterostructures. In this study, recent progress in the construction of BPNS-based heterostructures ranging from 2D hybrid structures to 3D networks is discussed, emphasizing the different types of interactions (covalent or noncovalent) between individual layers. The preparation methods, optical and electronic properties, and various applications of these heterostructures—including electronic and optoelectronic devices, energy storage devices, photocatalysis and electrocatalysis, and biological applications—are discussed. Finally, critical challenges and prospective research aspects in BPNS-based heterostructures are also highlighted